Active solid-state devices (e.g. – transistors – solid-state diode – Non-single crystal – or recrystallized – semiconductor... – Field effect device in non-single crystal – or...
Patent
1996-12-11
1998-12-01
Chaudhuri, Olik
Active solid-state devices (e.g., transistors, solid-state diode
Non-single crystal, or recrystallized, semiconductor...
Field effect device in non-single crystal, or...
257 67, 257 69, 257756, H01L 2976
Patent
active
058442561
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/JP96/01048 filled Apr. 17, 1996.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a semiconductor device and the manufacturing method thereof; and more particularly to an ultra LSI device equipped with a multi-layer interconnection structure configured by layering polycrystalline silicon interconnection layers separated by layers of insulation films, and the manufacturing method thereof.
2. Description of the Related Art
A memory cell of static random access memory (SRAM) usually consists of a pair of MOS transistors that form a flip-flop, two MOS transistors (transfer gates) that control the connection/disconnection of the output terminal and the data line, and two resistors that act as the load for the flip-flop.
However, as the integration level of SRAM has increased in recent years, SRAM is beginning to use memory cells in which the two resistors that act as the load for the flip-flop are replaced by two MOS transistors configured using thin polycrystalline silicon films. A single memory cell is thereby configured using six MOS transistors.
A MOS transistor (Thin Film Transistor: TFT) formed using thin polycrystalline silicon films is created by forming the source and drain layers by selectively introducing impurities into the polycrystalline silicon films formed on layer insulating films. Polycrystalline silicon films are also used as interconnection layers.
In other words, multi-layer thin-film polycrystalline silicon can be used for both interconnection and TFT configuration elements.
However, in LSI manufacturing, it is best to use common manufacturing processes as much as possible in order to reduce the number of process steps required. The inventor has discovered that when microcircuits are formed using the above-mentioned multi-layer thin-film polycrystalline silicon for both interconnection and TFT configuration elements using common manufacturing processes, an undesirable reverse-direction diode may sometimes be present in the current path.
In such case, the reverse-direction diode present in the current path interferes with the current supply, thus adversely affecting the circuit characteristics. Therefore, it is necessary to supply the current required for achieving the desired circuit characteristics by increasing the leakage current of the reverse-direction diode.
However, the reverse-direction diode consists of a polycrystalline silicon PN junction, and since no analysis had been performed on the leakage current characteristics of such a PN junction, no appropriate method was available for increasing the leakage current.
Therefore, one of the objects of the present invention is to successfully develop basic semiconductor manufacturing technology for achieving the required current supply capacity by increasing the amount of diode leakage current, i.e., the current that flows in the reverse direction, when a polycrystalline silicon PN junction diode (reverse-direction diode) is present in the current path. Another object of the present invention is to provide a highly-integrated, high-performance semiconductor device.
SUMMARY OF THE INVENTION
The present invention achieves the required current supply capacity by increasing the leakage current of a reverse-direction diode when the reverse-direction junction diode is present in the current path consisting of polycrystalline silicon, in a micro-patterned semiconductor device that uses thin-film polycrystalline silicon for both interconnection and TFT (Thin Film Transistor) configuration elements. Leakage current is increased by steepening the density slope at the PN junction of the diode which consists of polycrystalline silicon, or by making the region near the junction amorphous.
For example, sufficient current can be supplied to a large number of memory cells via reverse-direction diodes even when cells that use TFTs consisting of thin-film polycrystalline silicon as the load for the flip-flop are used as large-scale SRAM memory cells. In this way, ultra high-in
REFERENCES:
patent: 4835118 (1989-05-01), Jones, Jr. et al.
patent: 5289404 (1994-02-01), Okamoto
patent: 5526304 (1996-06-01), Kawamura
Chaudhuri Olik
Seiko Epson Corporation
Watson Mark P.
Wille Douglas A.
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